An alternate ammunition belt support for an automatic machine cannon is described in U.S. Pat. No. 3,759,136. In this known arrangement the discharge ducts for empty cartridge belt clips remain stationary over their entire length while in operation relative to the alternate belt feeder. This also applies to the alternate cartridge belt feeder parts which are connected to the weapon. For this reason the discharge ducts must be detachably connected to the alternate cartridge belt feeder. The change from one to the other type of ammunition feed is effected by means of a special arrangement. Thus, by means of a rotational movement the belt carrying the non-elected type of ammunition is placed out of engagement with a feed sprocket wheel, and the belt with the selected ammunition is, in lieu of the previous belt, placed in engagement with the feed sprocket wheel. When transferring to a larger caliber range this operation requires the application of a considerable force which can cause malfunctioning. In addition thereto the alternate feed mechanism must be pivoted away from the gun barrel weapon in order to carry out certain control functions of the weapon in order to obtain access to and a working space for the weapon. This requirement in the known arrangement to provide connections between discharge ducts and the alternate feed mechanisms such that these connections may be detached and re-established is considered advantageous. The therewith connected work input and time consumption is also considered as excessive and therefore undesirable.
An alternate ammunition belt feed mechanism whose position is adjustable relative to the gun barrel and therefore also relative to the discharge ducts for changing the ammunition cannot be achieved with the known afore-described gun carriage.